Section 7. Electrical equipment of special installations

Electrical installations in fire hazardous areas. Electric cars

Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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7.4.15. In fire hazardous areas of any class, electrical machines with voltage classes up to 10 kV can be used, provided that their shells have a degree of protection in accordance with GOST 17494-72 * not less than that indicated in Table. 7.4.1.

In fire hazardous areas of any class, electric machines purged with clean air with ventilation in a closed or open circuit can be used. In case of closed-loop ventilation, a device must be provided in the ventilation system to compensate for air losses and create excess pressure in machines and air ducts.

It is allowed to change the degree of protection of the shell against water penetration (2nd digit of the designation) depending on the conditions of the environment in which the machines are installed.

Until the electrical industry masters large synchronous machines, DC machines and static converter units in a shell with a degree of protection IP44, it is allowed to use machines and units with a degree of protection of the shell at least IP20 in fire hazardous zones of class P-IIa.

Table 7.4.1. Minimum allowable degrees of protection of shells of electrical machines, depending on the class of the fire hazard zone

* Until the electrical industry adopts IP54 machines, IP44 machines can be used.

7.4.16. Air for ventilation of electrical machines must not contain vapors and dust of combustible substances. Emission of exhaust air with an open ventilation cycle into a fire hazardous area is not allowed.

7.4.17. The electrical equipment of a portable electrified tool in fire hazardous areas of any class must be with a degree of protection of the shell of at least IP44; the degree of protection of the shell IP33 is allowed, provided that special technological requirements for the repair of equipment in fire hazardous areas are met.

7.4.18. Electric machines with parts that normally spark under the operating conditions (for example, electric motors with slip rings) must be located at a distance of at least 1 m from the places where combustible substances are located or separated from them by a fireproof screen.

7.4.19. For mechanisms installed in fire hazardous areas, it is allowed to use electric motors with a lower degree of shell protection than indicated in Table. 7.4.1, under the following conditions:

• electric motors must be installed outside fire hazardous areas;
• the drive of the mechanism must be carried out using a shaft passed through the wall, with a gland seal in it.

See other articles Section Rules for the installation of electrical installations (PUE).

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